package icom.example.circles;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;

/**
 * A list fragment representing a list of Circles. This fragment also supports
 * tablet devices by allowing list items to be given an 'activated' state upon
 * selection. This helps indicate which item is currently being viewed in a
 * {@link CircleDetailFragment}.
 * <p>
 * Activities containing this fragment MUST implement the {@link Callbacks}
 * interface.
 */
public class CircleListFragment extends ListFragment {

        /**
         * The serialization (saved instance state) Bundle key representing the
         * activated item position. Only used on tablets.
         */
        private static final String STATE_ACTIVATED_POSITION = "activated_position";

        /**
         * The fragment's current callback object, which is notified of list item
         * clicks.
         */
        private Callbacks mCallbacks = sDummyCallbacks;

        /**
         * The current activated item position. Only used on tablets.
         */
        private int mActivatedPosition = ListView.INVALID_POSITION;

        /**
         * A callback interface that all activities containing this fragment must
         * implement. This mechanism allows activities to be notified of item
         * selections.
         */
        public interface Callbacks {
                /**
                 * Callback for when an item has been selected.
                 */
                public void onItemSelected(String id);
        }

        /**
         * A dummy implementation of the {@link Callbacks} interface that does
         * nothing. Used only when this fragment is not attached to an activity.
         */
        private static Callbacks sDummyCallbacks = new Callbacks() {
                @Override
                public void onItemSelected(String id) {
                }
        };

        /**
         * Mandatory empty constructor for the fragment manager to instantiate the
         * fragment (e.g. upon screen orientation changes).
         */
        public CircleListFragment() {
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);

                // TODO: replace with a real list adapter.
                setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
                                android.R.layout.simple_list_item_activated_1,
                                android.R.id.text1, DummyContent.ITEMS));
        }

        @Override
        public void onViewCreated(View view, Bundle savedInstanceState) {
                super.onViewCreated(view, savedInstanceState);

                // Restore the previously serialized activated item position.
                if (savedInstanceState != null
                                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
                        setActivatedPosition(savedInstanceState
                                        .getInt(STATE_ACTIVATED_POSITION));
                }
        }

        @Override
        public void onAttach(Activity activity) {
                super.onAttach(activity);

                // Activities containing this fragment must implement its callbacks.
                if (!(activity instanceof Callbacks)) {
                        throw new IllegalStateException(
                                        "Activity must implement fragment's callbacks.");
                }

                mCallbacks = (Callbacks) activity;
        }

        @Override
        public void onDetach() {
                super.onDetach();

                // Reset the active callbacks interface to the dummy implementation.
                mCallbacks = sDummyCallbacks;
        }

        @Override
        public void onListItemClick(ListView listView, View view, int position,
                        long id) {
                super.onListItemClick(listView, view, position, id);

                // Notify the active callbacks interface (the activity, if the
                // fragment is attached to one) that an item has been selected.
                mCallbacks.onItemSelected(DummyContent.ITEMS.get(position).id);
        }

        @Override
        public void onSaveInstanceState(Bundle outState) {
                super.onSaveInstanceState(outState);
                if (mActivatedPosition != ListView.INVALID_POSITION) {
                        // Serialize and persist the activated item position.
                        outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
                }
        }

        /**
         * Turns on activate-on-click mode. When this mode is on, list items will be
         * given the 'activated' state when touched.
         */
        public void setActivateOnItemClick(boolean activateOnItemClick) {
                // When setting CHOICE_MODE_SINGLE, ListView will automatically
                // give items the 'activated' state when touched.
                getListView().setChoiceMode(
                                activateOnItemClick ? ListView.CHOICE_MODE_SINGLE
                                                : ListView.CHOICE_MODE_NONE);
        }

        private void setActivatedPosition(int position) {
                if (position == ListView.INVALID_POSITION) {
                        getListView().setItemChecked(mActivatedPosition, false);
                } else {
                        getListView().setItemChecked(position, true);
                }

                mActivatedPosition = position;
        }
}